UNIVERSITY    OF    CALIFORNIA 

COLLEGE    OF    AGRICULTURE 

AGRICULTURAL   EXPERIMENT   STATION 

CIRCULAR  No.  243 
June,  1922 

MARMALADE   JUICE   AND  JELLY  JUICE 
FROM  CITRUS  FRUITS 

By  W.  V.  CEUESS  and  LAL  SINGH 


The  profitable  use  of  cull  oranges  and  lemons  has  become  a  problem 
of  growing  importance  to  the  citrus  industry  because  of  the  rapid 
increase  in  production  in  recent  years.  If  the  market  for  the  fresh 
fruit  is  to  be  extended,  it  is  necessary  that  the  marketing  of  cull  fruit 
in  competition  with  graded  fruit  be  prevented  and  that  the  present 
high  standard  of  quality  of  the  latter  be  maintained. 

California  normally  produces  more  than  60,000  carloads  of  fresli 
citrus  fruits  annually  for  the  market.  Estimates  of  the  amount  of 
cull  fruit  vary  greatly,  but  it  represents  probably  at  least  5  per  cent 
of  the  total  production,  or  not  less  than  45,000  tons.  Some  of  this 
oull  fruit  is  at  present  utilized  in  the  preparation  of  citric  acid, 
marmalade,  orange  vinegar,  dried  peel,  citrus  juice,  etc.,  but  a  very 
large  proportion  is  discarded  or  sold  in  local  markets  in  competition 
with  the  graded  fruit.  In  years  when  frost  injury  is  serious,  the 
proportion  of  cull  fruit  is  greatly  increased. 

The  writers  believe  that  the  manufacture  of  two  products,  which 
we  have  called  " canned  marmalade  juice"  and  "jelly  juice,"  would 
afford  a  profitable  outlet  for  a  large  quantity  of  orange  culls.  These 
products  are  suitable  for  household  use  and  for  the  commercial 
preparation  of  marmalade  and  jelly.  They  would  save  the  housewife 
and  the  marmalade  manufacturer  the  expense  and  trouble  of  prepar- 
ing the  fresh  fruit  and  would  insure  more  uniformly  successful  results. 
Our  investigations  show  that  they  can  be  prepared  at  a  cost  sufficiently 
low  to  be  marketed  at  a  price  within  the  reach  of  the  average  con- 
sumer. Marmalade  or  citrus  jelly  made  from  the  canned  juice  is  much 
cheaper  than  similar  products  purchased  in  the  finished  state  or  pre- 
pared in  the  household  from  fresh  fruit  purchased  from  fruit  stores. 

Citrus  jelly  juice,  as  described  in  this  publication,  is  prepared  by 
boiling  sliced  oranges,  lemons,  or  grapefruit,  or  a  mixture  of  any  two 
or  all  of  these  fruits,  with  water,  and  then  expressing,  clarifying, 
canning  or  bottling,  and  sterilizing  the  liquid  so  obtained.     It  is  rich 


Z  UNIVERSITY    OF    CALIFORNIA — EXPERIMENT    STATION 

in  pectin  and  acid,  the  constituents  of  fruits  necessary  for  jelly  making. 
It  is  light  amber  in  color,  slightly  cloudy,  and  possesses  the  character- 
istic flavor  of  the  cooked  fruit.  When  concentrated  by  boiling  with 
the  proper  proportion  of  sugar  to  the  jelling  point  it  yields  a  clear, 
firm  jelly  of  light  amber  color  and  pleasing  flavor. 

Citrus  marmalade  juice  is  citrus  jelly  juice  to  which  has  been  added 
from  10  to  20  per  cent  of  boiled,  sliced  peel. 

These  products  may  be  prepared  and  canned  in  fruit  canneries  or 
in  marmalade  factories. 


Fig;  1. — Steam-jacketed  jelly  kettles  and  vacuum  pans  used  in  the  Fruit 
Products  Laboratory  for  heating  cut  fruit  and  for  concentrating  juice. 


RESULTS  OF  INVESTIGATIONS 

Kxperiments  upon  the  manufacture  of  marmalade  juice  were  first 
made  at  the  University  in  1915.  The  results  were  successful,  although 
no  attempt  was  made  at  that  time  to  investigate  the  details  of  the 
process.  During  the  past  six  months  one  of  the  writers  has  given  most 
of  his  time  to  a  careful  study  of  the  factors  involved  in  making  citrus 
jellies,  marmalades,  find  the  canned  juices  and  has  developed  a  method 
of  preparing  the  canned  juices  which,  it  is  believed,  can  be  applied 
upon  a  commercial  scale. 


Circular  243]  marmalade   juice   and   jelly   juice  3 

The  method  recommended  in  this  publication  is  based  upon  the 
results  of  these  investigations.  They  will  be  reported  fully  in  a  later 
publication.  A  brief  statement  of  the  results  of  the  experiments  having 
a  direct  bearing  on  the  subject  of  this  circular  is  given  herewith. 

1.  Unripe  oranges  yielded  a  bitter  juice,  as  did  much  of  the  fruit 
gathered  at  the  beginning  of  the  season,  even  when  complying  with 
the  8  : 1  standard. 

2.  It  was  found  better  to  cut  the  fruit  into  pieces  about  one-eighth 
of  an  inch  thick,  rather  than  one-quarter  or  one-half  of  an  inch  thick, 
for  boiling  and  extracting  the  juice. 

3.  Boiling  in  two  lots  of  water  in  successive  periods  of  45  minutes 
each  gave  the  best  results  with  respect  to  yield  and  clarification. 

4.  Pressing  the  boiled  fruit  gave  a  much  higher  yield  than  straining 
through  cloth  without  pressure. 

5.  The  most  effective  means  of  clearing  the  juice  was  found  to  be 
by  settling  and  racking  (drawing  off  the  clear  juice).  Filtration 
through  felt  bags  or  wood  pulp  gave  fairly  satisfactory  results. 

6.  Long  boiling  of  the  fruit  or  juice  in  copper  resulted  in  darken- 
ing the  color;  boiling  in  aluminum  and  glass-lined  equipment  did  not 
darken  the  color. 

7.  The  most  satisfactory  method  of  preparing  sliced  peel  for  mar- 
malade juice  was  found  to  be  the  following:  Cut  off  small  portions 
at  the  blossom  and  stem  ends  of  the  fruit.  Remove  the  remainder  of 
the  peel  in  quarters.  Cut  this  lengthwise  in  very  thin  slices  (about 
M.6  to  %2  of  an  mcn  thick). 

8.  Lemons  yielded  a  better  jelly  juice  than  a  mixture  of  oranges 
and  lemons.  A  mixture  of  equal  weights  of  lemons  and  oranges,  how- 
ever, was  almost  as  good  and  gave  a  product  much  superior  in  flavor, 
color,  and  general  appearance  to  that  made  from  the  usual  mixture 
of  10  per  cent  and  90  per  cent,  by  weight,  of  lemons  and  oranges, 
respectively.  Oranges  in  this  large  proportion  darkened  the  color  of 
the  juice  and  imparted  a  "stale"  or  "medicinal"  flavor.  Ten  per  cent, 
by  weight,  of  grapefruit  added  to  a  mixture  of  equal  weight  of  lemons 
and  oranges  gave  a  juice  of  pleasing  bitterness. 

9.  It  was  found  that  the  juice  should  contain  at  least  1  per  cent 
of  pectin  and  a  similar  amount  of  acid. 

10.  Marmalade  juice  canned  in  December,  1919,  at  the  present 
writing  (February,  1922),  still  retains  its  jelling  power  and  the  other 
desirable  qualities. 

11.  Juice  was  found  to  retain  its  color  and  flavor  better  in  lacquered 
cans  than  in  plain  tin  cans. 


UNIVERSITY    OF    CALIFORNIA — EXPERIMENT    STATION 


PEEPARATION  OF  MARMALADE  JUICE 

1.  Proportion  of  oranges  and  lemons. — Use  equal  weights  of  oranges 
and  lemons.  If  a  bitter  juice  is  desired  add  10  per  cent,  by  weight, 
of  grape  fruit. 

2.  Extracting  the  juice. — Slice  the  mixed  oranges  and  lemons 
about  Vs  of  an  inch  thick  or  crush  in  an  apple  grater.  Add  twice 
their  volume  of  water.    Boil  45  minutes.    Separate  the  juice  by  press- 


Fig.  2. — In  foreground,  press  used  in  Fruit  Products  Laboratory  for  extrac- 
tion of  juice.  In  background,  can  sealer.  At  left,  pressure  filters  and  vacuum 
pump. 

ing  or  draining  through  cheesecloth.  Add  enough  water  to  cover  the 
pulp  and  boil  again  for  45  minutes.  Press  again  and  combine  the 
juice  from  the  two  lots  and  strain  through  cloth. 

3.  Clearing  the  juice. — Set  the  juice  aside  overnight  in  5-gallon 
bottles  or  in  a  tank  that  will  not  be  affected  by  the  juice.  Pour  or 
siphon  off  the  juice  from  the  sediment  and  strain  through  a  felt  jelly 
bag.  The  juice  may  also  be  clarified  by  means  of  a  high-speed  centri- 
fuge or  by  nitration  through  wood  pulp  or  a  filter  press. 

4.  Concentration  of  the  juice. — Boil  the  juice  down  rapidly  until 
il  is  rich  enough  in  pectin  to  form  a  good  jelly.  If  the  juice  is  to  be 
canned  commercially,  it  is  suggested  that  it  be  concentrated  from 
K)    io  12°  Balling,  cold  test,  equivalent  to  about  1%°  to  3%°  Balling, 


Circular  243]  marmalade   juice   and   jelly   juice  5 

test  made  on  boiling  hot  juice.  Juice  of  this  concentration  will  make 
good  marmalade  or  jelly  when  one  cup  of  the  juice  is  mixed  with 
1%  to  2  cups  of  sugar  and  boiled  one  or  two  minutes.  If  concen- 
trated to  5°  or  6°  Balling,  only  one  cup  of  sugar  need  be  used  with 
each  cup  of  juice.  In  this  case  the  mixture  must  be  concentrated  by 
boiling  to  220°  or  221°  F.  Strain  the  hot  juice  through  filter  bags  or 
clarify  by  centrifuging. 

5.  Preparation  of  peels. — Remove  the  peel  in  quarters  from  large 
oranges  after  first  cutting  off  small  portions  from  the  blossom  and 
stem  ends.  Slice  the  peel  lengthwise  very  thin,  if  possible  to  V?^  of 
an  inch.  Peels  may  also  be  prepared  by  removing  a  broad  band  about 
%  of  an  inch  to  one  inch  wide  around  the  greatest  circumference  of 
the  fruit  and  cutting  these  ribbons  of  peel  in  very  thin  shreds  about 
%  inch  to  one  inch  long.  Boil  the  peels  until  tender,  then  discard  the 
water.     Allow  to  drain  on  a  screen. 

6.  Addition  of  peel  to  juice. — To  cold  juice  (60°-64c  F.)  testing 
10°-12°  Balling,  add  about  twenty  parts,  by  weight,  of  shredded  peel 
to  100  parts  by  weight  of  juice,  or  iy2  pounds  of  peel,  per  one  gallon 
of  juice.  To  juice  testing  6°  Balling  cold,  add  %  of  a  pound  of  peel 
per  gallon  of  juice. 

7.  Testing. — Prepare  one  or  more  glasses  of  marmalade  from  each 
lot  to  make  certain  that  the  product  will  jell.  If  the  juice  is  of  10° 
to  12°  or  more  Balling  (cold  test),  the  product  should  make  jelly 
when  1%  or  2  cups  of  sugar  are  added  to  one  cup  of  juice  and  the 
mixture  is  boiled  about  two  minutes.  If  the  juice  is  of  about  6°  Ball- 
ing (cold  test),  add  one  cup  of  sugar  to  one  cup  of  juice  and  boil  to 
221°  F.,  or  until  the  boiling  marmalade  will  hang  in  sheets  from  a 
cooking  spoon.  If  the  test  shows  the  juice  to  be  deficient  in  pectin, 
concentrate  it  to  such  a  Balling  degree  that  good  jelly  can  be  prepared 
from  it  without  difficulty. 

8.  Canning  and  sterilizing. — Heat  the  mixture  of  peels  and  juice 
to  boiling  without  adding  sugar  and  place  in  jars  or  lacquered  cans 
while  boiling  hot.  Fill  cans  completely.  Seal  immediately  and  invert 
to  cool. 

9.  Recipe  for  use. — The  label  should  carry  a  suitable  and  simple 
recipe  for  the  use  of  the  contents  of  the  can.  For  juice  of  10°-12° 
Balling  prepared  as  above  this  may  be :  "To  each  cup  of  this  juice  and 
peel  add  from  1%  to  2  level  cups  of  sugar.  Boil  about  two  minutes. 
Skim  and  pour  into  glasses." 

If  the  liquid  is  of  only  6°  Balling,  the  recipe  may  read:  "To  each 
cup  of  juice  and  peel,  add  one  level  cup  of  sugar.  Boil  until  a  ther- 
mometer inserted  in  the  boiling  juice  reads  221°  F.,  or  until  the  liquid 
will  hang  in  sheets  (jell)  when  allowed  to  fall  from  a  spoon." 


6  UNIVERSITY   OF    CALIFORNIA — EXPERIMENT    STATION 

The  writers  prefer  the  juice  of  higher  concentration  (10°  Balling) 
because  its  use  requires  no  previous  experience  on  the  part  of  the  user. 

A  good  dairy  thermometer  is  convenient  for  taking  the  temperature 
of  the  juice.    A  Balling  hydrometer  of  good  quality  and  reading  to  %0° 


Fig.  3. — Balling  hydrometer,  hydrometer  cylinder,  and  thermometer. 

should  be  employed.  A  copper  hydrometer  cylinder  about  1%  inches 
wide  and  15  to  18  inches  deep  is  very  convenient  for  holding  samples 
of  juice. 


EFFECT  OF  TEMPERATURE  ON  BALLING  TEST 

I  Jailing  hydrometers  are  standardized  for  use  at  60°  F.  In  the 
process  of  preparation  of  the  jelly  juice,  the  test  must  be  made  upon 
the  hoi  Liquid,  usually  at  180-200°  F.  Since  a  rise  in  temperature 
causes  Liquids  to  expand,  the  Balling  hydrometer  will  give  readings 
that  are  too  low.     Data  from  tables  which  give  the  effect  of  temperature 


CIRCULAR  243]  MARMALADE    JUICE    AND    JELLY    JUICE  7 

upon  the  Balling  test  have  been  arranged  in  such  manner  that  the 
Balling  degrees  in  the  table  are  those  of  a  juice  of  10°  Balling  (60°  P.) 
heated  to  the  temperatures  shown  in  the  table. 

Thus,  if  the  juice  is  tested  at  190°  F.  it  must  be  concentrated  until 
the  Balling  hydrometer  will  indicate  at  this  temperature  2.2°-4.1° 
Balling  if  a  juice  of  10°-12°  Balling  is  desired;  or  if  the  test  is  made 
at  150°  F.,  the  instrument  must  show  5.5°-7.5°  Balling,  and  similarly 
for  other  temperatures. 

TABLE  1 
Effect  of  Temperature  on  the  Beading  of  a  Balling  Hydrometer 


Temperature 
of  juice 
Deg.  F. 

Balling  degree  of 

juice  equivalent 

to  10  cleg.  Balling 

cold  test 

Temperature 
of  juice 
Deg.  F. 

Balling  degree  of 

juice  equivalent 

to  10  deg.  Balling 

cold  test 

60 

10.00 

130 

6.9 

68 

9.90 

140 

6.2 

7.1 

9.60 

150 

5.5 

90 

9.00 

160 

4.7 

100 

8.50 

170 

3.9 

no 

S.00 

180 

3.1 

190 

2.2 

120 

7.50 

200 

1.2 

PREPARATION  OF  JELLY  JUICE 


Use  equal  amounts  of  thinly  sliced  oranges  and  lemons  and  proceed 
as  directed  above  for  the  preparation  of  marmalade  juice,  but  omit 
steps  5  and  6.     This  product  is  canned  without  the  addition  of  peel. 


SUMMARY 


1.  The  uncertainty  and  most  of  the  labor  of  making  citrus  fruit 
jelly  and  marmalade  in  the  home  can  be  eliminated  by  the  use  of  con- 
centrated canned  citrus  jelly  juice  and  marmalade  juice.  These  juices 
can  be  prepared  in  canneries  in  the  citrus  growing  districts,  by 
methods  described  above,  and  distributed  through  the  usual  trade 
channels.  The  cost  to  the  housewife  of  juice  and  sugar  to  make  a 
6-ounce  glass  of  marmalade  or  jelly  will  not  exceed  five  cents.  The 
canned  juices  are  also  suitable  for  use  in  the  preparation  of  marmalade 
and  jelly  upon  a  commercial  scale. 

2.  The  jelly  juice  is  prepared  by  boiling  sliced  oranges  and  lemons 
(equal  weight  of  each)  with  water  and  pressing,  followed  by  strain- 
ing, settling,  drawing  off  the  juice  from  the  sediment,  filtering,  and 


<5  UNIVERSITY   OF    CALIFORNIA EXPERIMENT    STATION 

concentrating  by  boiling.  The  juice  is  filled  boiling-  hot  into  lacquered 
cans  and  sealed  at  once.  Marmalade  juice  is  prepared  in  the  same 
manner,  except  that  thinly  cut  boiled  peel  is  added  at  the  time  of 
canning. 

3.  A  higher  yield  of  pectin  is  obtained  by  the  use  of  fruit  cut  to 
Vs  of  an  inch  in  thickness  or  less  than  from  that  cut  14  of  an  inch  or 
thicker. 

4.  Boiling  for  an  hour  and  a  half  is  necessary  to  obtain  a  maximum 
yield  of  pectin.  The  juice  is  more  easily  cleared  and  the  yield  of  pectin 
is  increased  if  the  fruit  is  boiled  and  leached  with  two  lots  of  water 
for  45  minutes  in  each  case  (a  total  of  iy2  hours). 

5.  The  juice  should  contain  at  least  1  per  cent  of  acid  and  pectin, 
respectively. 

6.  The  writers  believe  that  canned  marmalade  juice  and  to  a  less 
degree  canned  citrus  jelly  juice  possess  sufficient  merit  to  make  their 
commercial  production  worthy  of  serious  consideration  by  canners  and 
manufacturers  of  citrus  by-products.  Their  production  should  afford 
a  profitable  means  of  utilizing  fruit-canning  equipment  during  the 
winter  and  spring  months. 


